1. Field of the Invention
This invention relates to a method for reducing fuel consumption in an internal combustion engine. More particularly, this invention relates to a method for reducing fuel consumption in an internal combustion engine by incorporating an additive in the fuel to increase fuel economy and to a fuel composition for an internal combustion engine containing said additive, wherein the additive comprises an ester of a polyhydric polyether having ether oxygens and free and esterified hydroxyl groups in the polyhydric polyether backbone of the ester molecule.
2. Background of the Disclosure
There are continuing efforts to reduce fuel consumption in internal combustion engines for motor vehicles and for other applications. These include gasoline and diesel fuel powered engines. Considerable effort has been spent over the years in developing and improving friction reducing additives for the engine lubricating oil. These additives have included a wide variety of organic compounds, including compounds which contain one or more of metal, nitrogen and sulfur. Lubricating oil compositions containing fatty acid esters and amides, both sulfurized and unsulfurized, are disclosed, for example, in U.S. Pat. Nos. 4,201,684 and 5,154,844. In addition, many other additives are added to the oil such as antioxidants, detergents, dispersants, antiwear compounds, viscosifiers, pour point depressants, antifoam agents and the like. However, the improvements in fuel efficiency obtained with improvements in lubricating oil friction reducing additives have been modest and are typically difficult to ascertain without statistical testing in a number of internal combustion engines. Increasing effort is now being spent in developing fuel additives as friction modifiers to provide greater fuel economy by reducing friction in the combustion chamber of an internal combustion engine.
The development of additives for fuel has drawn on the experience gained with additives developed for lubricating oils, but the conditions in an internal combustion chamber are substantially different from, and much more sever than, those in a crankcase. Consequently, the fact that a particular additive or class of additives has benefited the performance of a lubricating oil in an internal combustion engine does not mean that benefits will be gained by using the same types of compounds as additives in the fuel. Fuel additives for increasing fuel economy in an internal combustion engine have included esters of fatty acids and polyhydric alcohols such as glycerol, as disclosed in U.S. Pat. No. 4,617,026. The '026 patent also discloses that fatty acid esters of a polyether such as a polyalkylene glycol have been used in lubricating oils.